Apparatus and process for purifying airplane engine oil



Jan. 6, 1942. A. E. FLOWERS 2,268,653 APPARATUS AND PROCESS FOR FURIFYING AiRPLANE ENGINE OIL Filed Sept. 18, 1940 CE/Yf/F/FVGAL JEPA/FAfOE 0/4 M072? T EE -1 R L if PEZIEFVAll/E 4 PUMP 0/ TA/VK 1 Pump 6 11/777555.- J W v fl/d/Z 5. 670106) P KY- w Patented Jan. 6,1942

UNITED STATES PATENT OFFICE APPARATUS AND PROCESS FOR PURIFYING AIRPLANE ENGINE OIL Alan E. Flowers, Poughkeepsie, N. Y., assignor to The De Laval Separator Company, New York,

N. Y., a corporation of New Jersey 11 Glalms.

The object of my invention is to purify oil for lubricating airplane engines while theairplane is in flight.

With all engines, and particularly internal combustion engines, there is, during operation, a continuous contamination of the oil used for lubricating them. The impurities consist principally of particles of metal from the wearing surfaces, carbon formed from disintegration of the oil and incomplete combustion of the fuel, and gummy material from oxidation, polymerization and cracking of. the oil. This progressive accumulation of impurities in the oil is exceptionally troublesome in the engines of large planes on long flights and, in order to prevent the density of impurities exceeding a workable limit, the quantity of oil carried is larger than would otherwise be required.

It is well known that'if, from a body of liquid to which impurities are being-continuously added, a small stream is drawn off, purified and returned to the body, it is possible to prevent the concentration of impurities exceeding a small figure. This "by-pass. method of maintaining the" purity of the circulating oil is disclosed in the Kennedy Patent No. 1,318,086, issued October 7, 1919. With a known rate of addition of impurities, 'it is possible to calculate the quantity of liquid that must be purified in a given time to maintain the desired degree of purity.

' The best known means for removal of such impurities from lubricating oil is by centrifugal purifiers and. hundreds of these devices are now in use on land and sea.

' There are two systems now in extensive use for driving purifiers for land and marine engines. One of these is direct mechanical drive from the engine. Because of great and sometimes sudden variations in engine speed this system is not feasible on an airplane. The other is by electric motor, but this requires excessive weight.

I have found that during the time that the engine is operating, there are two continuously flowing streams ,of oil, both under pressure. One of these, cool air-free oil from the storage tank to the engine, i provided by a pump having a capacity only a little greater than that required for lubrication, and is at a pressure needed for that purpose. The other stream is of hot oil being returned from the engine, through a cooler, to the storage tank. In order to be sure to draw from the sump of the engine all the oil. and with it, any gases that may blow by the pistons, the

pump for this stream must have a capacity far in excess of the .oil to be pumped and hence the oil is fully charged with air or other gases.

Oil in the first stream, being freed of air or other gases in tank 2, is in condition for centrifugal purification and a small by-pass may be taken from it, purified and returned to the system.

Even though the second stream is heavily charged with gases,'it is suitable for motive fluid in a small turbine and a part, or all .ifnecessary, may be used to operate a purifier.

The accompanying drawing shows, in diagram. two embodiments of my invention, each comprising an airplane engine, its lubrication system, and an oil purifier adapted for operation in accordance with the above description.

Referring, first, to the embodiment shown in Fig. 1: The oil circulating system through the airplane engine I comprises the oil tank 2, the oil conduit 3 from the tank to the engine with a pump 4 for forcing the oil' through conduit 3 and a conduit 5 with a pump 6 for forcing the oil under high pressure from the engine I through a cooler 1 to the tank 2. The centrifugal purifier 8 is driven by a motor 9 operated by oil under pressure flowing through a branch or by-pass comprising a passage ID from the oil return pipe 5 to the motor 9 and a passage II from the motor a to the tank 2. A small tream of oil free from air flows from the oil outflow conduit 3 through a passage l2, the interior of the purifier 8 and a passage l3 to the tank 2, the passage I3 preferably joining with passage l I, the-purified oil thus being returned to the oil circulating system at a rate adequate to maintain the desired degree of purity of the oil. A relief valve l5, by opening' and allowing oil to by-pass from passag ill to passage ll if the pressure exceeds a predetermined value, prevents danger of the purifier 8 being driven at excessive speed.

In Fig. 2 parts corresponding to the apparatus of Flg. 1 have applied thereto the same numbers, primed. The operation of this apparatus is v the same as that of the apparatus .of Fig. 1 except that all of the ofl being returned from the engine l' to the tank 2' is passed through the turbine 9'. What I claim and desire to protect by Letters Patent is:

1. The combination with an airplaneeengine and alu'bricating oil circulation system comprising an oil tank and conduits through/which oil is forced from the tank to the engine and from the engine to the tank, of oil purifying means comprising a centrifugal purifier and an oil driven motor adapted to drive the purifier, means to pass through the motor oil fiowing as aforesaid from the engine to the tank to thereby drive the motor and purifier, and means to by-pass through the interior of the purifier a part of the oil fiowing from the tank toward the engine.

2. The combination with an airplane engine and a lubricating oil circulation system comprising an oil tank and conduits through which oil is forced from the tank to the engine and from the engine to the tank, of oil purifying means comprising a centrifugal purifier and an oil driven motor adapted to drive the purifier, means to pass through the motor oil flowing as aforesaid from the engine to the tank to thereby drive the motor and purifier, and means to by-pass through 1 the interior of the purifier and thence to the tank a part of the oil flowing from the tank toward the engine.

3. The combination with an airplane engine and a lubricating oil circulation system comprising an oil tank and conduits through which oil is forced from the tank to the engine and from the engine to the tank, of a centrifugal purifier, means operable by oil flowing from the engine to the tank to drive the purifier, and means to pass through the interior of the purifier a part of the oil flowing from the tank and return it in a purified condition to the system.

4. The combination with an airplane engine and a lubricating system therefor including an oil tank, a conduit and a relatively low capacity pump for forcing gas-free oil therethrough from the tank to the engine, a second conduit and a relatively high capacity pump for returning oil and occluded gases from the engine to the tank, of oil purifying means comprising a centrifugal oil purifier with a driving motor adapted for operation by oil in the second conduit in its passage from the engine to the tank and means to by-pass a portion of the oil from the first named conduit through the purifier and back to the circuit. p

5. The combination with an airplane engine and a lubricating system therefor including an oil tank, a conduit and a relatively low capacity pump for forcing gas-free oil therethrough from the tank to the engine, a second conduit and a relatively high capacity pump for returning oil and occluded gases from the engine to the tank, of oil purifying means comprising a centrifugal oil purifier with a driving motor adapted for operation by oil in the second conduit in its pas- .sage from the engine to the tank, mean to bypass a portion of the oil from the first named conduit through the purifier and back to the circuit, and regulating means to limit to a predetermined pressure the fiow of the stream of gas-laden oil through the oil-driven motor.

6. The combination with an airplane engine of an oil tank, a conduit through which gas-freeoil is forced from the tank to the engine, oil purifying means comprising a centrifugal purifier and a motor adapted to drive the purifier, meansto 'by-pass through the interior of the purifier a part of the oil flowing from the tank toward the engine, said motor being adapted for operation by oil under pressure, and conduits through which oil and occluded gases are simultaneously rebeing operable. by the oil flowing through one of f the last named conduits.

'7. The combination with an airplane engine and a lubricating system therefor including an oil tank, a conduit and a relatively low capacity pump for forcinggas-free oil therethrough from the tank to the engine, a second conduit and a relatively high capacity pump for returning oil and occluded gases from the engine to the tank, of oil purifying means comprising a centrifugal purifier and a driving motor adapted to be operated by oil, means to by-pass a portion of the gas-free oil from the first conduit through the purifier, and means to by-pass a portion of the oil and occluded gases from the second conduit through the motor to drive the same.

8. The combination with an airplane engine and alubricating system therefor comprising a tank, relatively low capacity means to force a stream of gas-free cool oil from 'the tank to the engine, relatively high capacity means to force a stream of gas-laden hot oil from the engine to the tank, of a centrifugal purifier, means to divert some of the gas-free cool oil through the interior of the purifier and, back to the circuit, anda motor driving the purifier and operable by said stream of gas-laden hot oil.

9. The combination with an airplane engine and a lubricating system therefor comprising a tank, relatively low capacity means to force a stream of gas-free cool oil from the tank to the engine, relatively high capacity means to force a stream of gas-laden hot oil from the engine to the tank, of a centrifugal purifier, means to divert some of the gas-free cool oil through the interior of the purifier and back to the circuit, and a motor driving the purifier and operable by said stream of gas-laden hot oil, and regulating means to limit to a predetermined maximum pressure the flow of the stream of gas-laden hot air through the oil-driven motor.

10. In a lubricating oil system for airplane engines in which gas free oil fiOWs from an oil supply to the engine and in. which oil and 00- turned from the engine to the tank, said motor cluded gases fiow from the engine back to the tank, the process of maintaining a desired degree of purity of the oil while the airplane is in flight which comprises by-passing part of the gas-free oil flowing toward the engine andreturning it to the circuit, and utilizing the energy derived from the gas-laden oil flowing from the engine to the oil supply to effect centrifugal purification of said by-passed gas-free oil.

11. In a lubricating oil system for airplane engines comprising an oil supply, an endless circuit from the oil supply to the engine and back to the oil supply, a. by-pass across the circuit and a centrifugal purifier in said by-pass, the process which comprises pumping the oil at relatively low pressure from the supply to the engine and at relatively high pressure from the engine to the supply, utilizing energy derived from oil flowing at relatively high zpressure from the engine to the supply, to drive the purifier and regulating the power required to drive the purifier by by-passing oil pumped from the engine to the supply to limit the pressure of the purifier-driving oil to a predetermined value.

ALAN E. FLOWERS. 

